This invention relates to a device control technology for a compound computer system in which a plurality of computers and a plurality of I/O devices are connected with each other via peripheral component interconnect (PCI) switches, and more particularly, to control for handing a failure which has occurred in an I/O device shared by a plurality of computers.
IT systems used for processing for task-related information in companies are configured by various servers including WEB servers for displaying information to users information on respective tasks, application (AP) servers for integrating and processing information, database (DB) servers for accumulating and storing information, and the like. Those servers use computers, each including a CPU, a memory, and I/O devices. The IT system is configured by a large number of servers as described above, and hence, in order to simplify management of the servers, blade servers in which a plurality of computers are installed in one apparatus have been employed (refer to JP 2002-32153 A).
The processing performance of a CPU used for a computer has been increased in recent years by means of a multi-core configuration in which the CPU includes a plurality of processor cores, and a virtual server technology has been employed for operating a plurality of virtual servers on one computer for efficient use of the CPU. Further, computers use I/O devices such as a network interface card (NIC), and a fiber channel-host bus adaptor (FC-HBA) for network communication with other computers and connection to storage systems.
While a plurality of serves operate on one computer, the number of I/O devices which are connectable to the one computer has not increased due to physical constraint, and the number of I/O devices per computer is relatively insufficient.
Technologies for making up for the insufficient number of I/O devices include a multi-root I/O switch technology which enables a plurality of computers and a plurality of I/O devices to connect with each other, and a multi-root IO virtualization (IOV) technology for enabling a plurality of computers to share one I/O device. The multi-root I/O switch technology enables to change, in a scalable manner, the number of I/O devices which are connectable to one computer (see “Advanced Switching Technology Tech Brief”, issued in 2005, written by ASI-SIG, for example; hereinafter, referred to as Non-patent Document 1). The multi-root I/O virtualization technology enables to increase, by sharing one I/O device by a plurality of computers, the number of I/O devices in a virtual manner. By using those technologies, it is possible to solve the problem of the insufficient number of I/O devices when virtual servers are used (see U.S. Pat. No. 7,058,738).
The blade server which contains a plurality of computers in an enclosure is described in JP 2002-32153 A titled “CARTRIDGE TYPE SERVER UNIT AND A CABINET TO ACCOMMODATE A PLURALITY OF SAID SERVER UNITS”. The multi-root I/O switch technology of this type is described in Non-patent Document 1.